aboutToAppear() {
    this.getStreaming()
    globalWindowClass.setKeepScreenOn(true, (err) => {
      if (err.code) {
        console.error('Failed to set the screen to be always on. Cause: ' + JSON.stringify(err));
        return;
      }
      console.info('Succeeded in setting the screen to be always on.');
    });
    let _this = this
    this.conn.register((error) => {
      Logger.info(TAG, "net is available, err: " + JSON.stringify(error));
    })
    this.conn.on('netUnavailable', (data => {
      // promptAction.showToast({
      //   message: "net is unavailable, netId is " + String(data),
      //   duration: 2000
      // });
      Logger.info(TAG, "net is unavailable, netId is " + JSON.stringify(data));
    }));
    //网络可用回调
    this.conn.on('netAvailable', (data => {
      // promptAction.showToast({
      //   message: "net is available, netId is " + String(data),
      //   duration: 2000
      // });
      Logger.info(TAG, "net is available, netId is " + JSON.stringify(data));
      if (this.isFirst) {
        _this.timeObj && clearTimeout(_this.timeObj)
        if (!_this.isTime) {
          _this.getStreaming()
        }
      }
      this.isFirst = true
    }))
    //网络断开回调
    this.conn.on('netLost', (data) => {
      _this.isTime = false;
      _this.startCount();
      Logger.info(TAG, 'netLost');
    })

  }
